Prefragmented warheads with enhanced performance

ABSTRACT

A deliverable weapon, such as a missile, an artillery round, an aerial bomb, or a mortar round, having an explosive warhead, utilizes concentric annular sleeves that upon detonation provide placement of smaller fragments of an inner annular sleeve interstitially with respect to larger fragments of an outer annular sleeve in an expanding fragmentation curtain that contains expanding gases to increase the pressure of the explosion and the kinetic energy transferred to the fragments. In embodiments, the sleeves are comprised of ordered layers of spherical metal fragments encased in binder material and an outer casing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/311,737, filed Mar. 22, 2016, which is hereby fullyincorporated herein by reference.

FIELD OF THE TECHNOLOGY

The present disclosure relates generally to weapons and, moreparticularly, to warheads including preformed fragments.

BACKGROUND

When U.S. military personnel go into battle, they rely on sophisticatedand efficient weaponry to defeat enemy forces. In an effort to reducethe number of causalities suffered by U.S. forces, modern weapons aredesigned to deliver payloads from great distances with uncanny accuracy.Examples of these modern weapons include guided missiles, guided bombsdropped from aircraft including unmanned aerial vehicles (UAVs), andguided artillery shells. The primary destructive power of these weaponsis provided by the warheads they carry.

Warheads are used in a variety of military applications to deliver adistribution of high-velocity fragments across a target area. Thepenetration effectiveness of a fragment when it strikes a target isdirectly proportional to the fragment's kinetic energy. The fragmentskinetic energy is derived from an explosion. An explosion is a rapidincrease in volume and release of energy accompanied by the generationof high temperatures and the release expanding gases. Supersonicexplosions created by high explosives are known as detonations andtravel via supersonic shock waves.

SUMMARY OF THE INVENTION

A deliverable weapon, such as a missile, an artillery round, an aerialbomb, a mortar round, or a grenade, having an explosive warhead,utilizes concentric annular sleeves that upon detonation provideplacement of smaller fragments of an inner annular sleeve interstitiallywith respect to larger fragments of an outer annular sleeve in anexpanding fragmentation curtain that contains expanding gases toincrease the pressure of the explosion and the kinetic energytransferred to the fragments. In embodiments, the sleeves are comprisedof ordered layers of spherical metal fragments encased in bindermaterial and an outer casing.

According to an example embodiment, a warhead for a deliverable ornon-deliverable weapon comprises an explosive charge and a first sleevecomprising a first set of uniform sized spherical fragments embedded ina binder disposed about the explosive charge. The warhead also includesa second sleeve comprising a second set of uniform sized sphericalfragments embedded in a binder and disposed about the first sleeve. Inthis example embodiment, the first set of fragments comprise smallfragments and the second set of fragments comprise large fragments. Thewarhead may also include a housing containing the first sleeve, thesecond sleeve, and the explosive charge.

In some example embodiment, the second sleeve has a single row ofspherical fragments in an ordered arrangement. In some exampleembodiments, the arrangement of the spherical fragments may be somewhatchaotic generally due to the fragment sleeve thickness being greaterthan the fragment diameter. In some example embodiments, the largefragments in the second set of fragments are arranged in a plurality ofaxial columns and circumferential rows with adjacent circumferentialrows being offset from one another in an axial direction and adjacentaxial columns being offset from one another in a circumferentialdirection. It is contemplated that the fragments may have variousnon-spherical shapes in some embodiments.

In some cases, the large fragments are larger than the small fragmentsdiametrically by at least 50%. In other embodiments, the large fragmentsare larger than the small fragments diametrically by at least 100%. Inembodiments, volumetrically, the large fragments are at least 300%larger than the small fragments. In embodiments, volumetrically, thelarge fragments are at least 600% larger than the small fragments.

In some cases, the mean sizes of the large fragments are larger than themean size of the small fragments diametrically by at least 50%. In otherembodiments, the means size of the large fragments are larger than themean size of the small fragments diametrically by at least 100%. Inembodiments, volumetrically, the mean sizes of the large fragments areat least 300% larger than the mean size of the small fragments. Inembodiments, volumetrically, the mean sizes of the large fragments areat least 600% larger than the mean size of the small fragments. Inembodiments, substantially all of the large fragments are larger thansubstantially all of the small fragments. In some cases, the mean sizesof the greatest linear dimension of the large fragments are larger thanthe mean size of the greatest linear dimension of the small fragments byat least 50%. In other embodiments, the means size of the greatestlinear dimension of the large fragments are larger than the greatestlinear dimension of the mean size of the small fragments by at least100%. In other embodiments, the means size of the greatest lineardimension of the large fragments are larger than the greatest lineardimension of the mean size of the small fragments by at least 300%.

In some example embodiments, the first sleeve is disposed between theexplosive charge and the second sleeve so that expanding gases producedby the explosive charge upon detonation push the small fragments intocontact with the large fragments. Also in some example embodiments, thesmall and large fragments have curved outer surfaces that facilitatemigration of the small fragments into interstitial spaces between thelarge fragments when small fragments are forced into contact with largefragments upon detonation of the explosive charge so that the flow ofthe expanding gases through the interstitial spaces is restricted by thesmall fragments. The small fragments and the large fragments may form anexpanding fragmentation curtain that provides improved containment ofexpanding gases compared to other fragmentation arrangements, andincreases the total kinetic energy of the fragments.

The acceleration of the smaller fragments compared to the largerfragments, presuming common densities, varies with the inverse of theradii of the fragments. Thus, under the same explosive pressure, thelarger fragments will not accelerate as fast as the smaller fragments,and immediately post detonation, will have less velocity and lesskinetic energy. Placing small fragments interior to the large fragmentssuch that the small fragments acceleration is impeded by largerfragments, the small and large fragments coalesce into a curtainimmediately after the explosion providing an enhanced dynamiccontainment of the expanding gases increasing the pressure of theexplosion and ultimately the kinetic energy of the fragments. Thus, afeature and advantage of embodiments of the invention is that with thebound uniform small fragments interior to the bound large fragments inan explosive condition, after the small and large fragments are unboundas the binder disintegrates, the small and large fragments provide animproved coalescence, that is, a generally greater density of fragmentslarge and small, providing improved containment of the expandingexplosive gases, increasing the explosive pressure providing enhancedacceleration and velocity to the fragments, large and small, andproviding a net increase in kinetic energy of the totality of thefragments.

In some example embodiments, the first wall of the first sleevecomprises a first binding material, the second wall of the second sleevecomprises a second binding material, and the first binding material issubstantially the same as the second binding material. In some exampleembodiments, the first binding material and/or the second bindingmaterial may comprise a thermoplastic resin. In some exampleembodiments, the first binding material and/or the second bindingmaterial may comprise a thermosetting polymer. In some exampleembodiments, the first binding material and/or the second bindingmaterial may comprise an epoxy.

In some example embodiments, the first binding material and the secondbinding material hold the small fragments separate from the largefragments prior to detonation of the explosive charge and the firstbinding material and the second binding material break into piecesand/or disintegrate upon detonation of the explosive charge so that thesmall fragments and the large fragments are free to contact each other.

In some example embodiments, the small fragments and the large fragmentshave a first infrangibility, the first binding material and the secondbinding material have a second infrangibility, and the firstinfrangibility is greater than the second infrangibility. It iscontemplated that small fragments and/or large fragments may be deformedafter detonation of explosive charge. Whether or not the fragments aredeformed, the infrangibility of the fragments may be sufficient toprevent each fragment from breaking into a plurality of pieces.

In some example embodiments, the binding material is generally frangibleand the fragments generally are not; stated differently, the firstbinding material is more frangible than the first fragments and thesecond binding material is more frangible than the second fragments.That is, for example, during the detonation of the explosive charge thefirst binding material disintegrates and the first fragments mostlyremain intact; additionally the second binding material disintegratesand the second fragments mostly remain intact.

In embodiments, the binding material is generally frangible and thefragments are generally are not. The fragments are ductile and thebinding material is not. In embodiments, upon detonation, the bindingmaterial is generally frangible and the fragments are generally are not,and the fragments are ductile and the binding material is not.

In some example embodiments, the small fragments and the large fragmentscomprise the same material. For example, the small fragments and thelarge fragments may both comprise a tungsten alloy or they may comprisesteel.

In some example embodiments, the majority of the small fragments in thefirst set of fragments have a generally spherical outer surface. Forexample, substantially all of the small fragments in the first set offragments have a generally spherical outer surface in some embodiments.In some example embodiments, the majority of the small fragments in thefirst set have substantially equal diameters. For example, substantiallyall of the small fragments in the first set of fragments may havesubstantially equal diameters in some embodiments.

In some example embodiments, the majority of the large fragments in thesecond set of fragments have a generally spherical outer surface. Forexample, substantially all of the large fragments in the second set offragments have a generally spherical outer surface in some embodiments.

An illustrative method of manufacturing a warhead may include loading afirst multiplicity of spherical fragments of a uniform first size withina first annular containment in an ordered arrangement and filling thefirst annular containment with a first annular containment binder for atleast substantially covering the first multiplicity of sphericalfragments. The first annular containment binder may have a flowablecondition to facilitate filling of the first annular containment. Theillustrative method may include allowing the binder to harden whereinthe spherical fragments are embedded within the first annularcontainment binder in a first annular form having the shape of the firstannular containment. This illustrative method may also include loading asecond multiplicity of spherical fragments of a uniform second sizewithin a second annular containment having a wall surface thatcorresponds to a wall surface of the first annular containment. Thismethod may additionally include filling the second annular containmentwith a second annular containment binder for at least substantiallycovering the multiplicity of spherical fragments. The second annularcontainment binder may have a flowable condition to facilitate fillingof the second annular containment. The method may include allowing thesecond annular containment binder to harden wherein the sphericalfragments are embedded within the second annular containment binder in asecond annular form with the shape of the second annular containment. Anexplosive material may be positioned within a cavity defined by theannular forms. The first annular form, the second annular form and theexplosive material may be positioned within a housing with one annularform interior to the other annular form.

In embodiments, a method of manufacturing a warhead comprises, loading afirst multiplicity of spherical fragments of a uniform first size withina first annular containment in an ordered arrangement; filling the firstannular containment with a first annular containment binder for at leastsubstantially covering the first multiplicity of spherical fragments,the first annular containment binder having a flowable condition;allowing the binder to harden wherein the spherical fragments areembedded within the first annular containment binder in a first annularform having the shape of the first annular containment; loading a secondmultiplicity of spherical fragments of a uniform second size within asecond annular containment having an inner wall surface thatdimensionally corresponds to an outer wall of the first annularcontainment, the uniform second size diametrically at least 50 percentlarger than the uniform size of the first multiplicity of sphericalfragments; filling second annular containment with a second annularcontainment binder for at least substantially covering the multiplicityof spherical fragments, the first annular containment binder having aflowable condition; allowing the second annular containment binder toharden wherein the spherical fragments are embedded within the secondannular containment binder in a second annular form with the shape ofthe second annular containment; positioning explosive material within acavity defined by the first annular form; and affixing the first annularform and the second annular form within a housing with the first annularform interior to the second annular form; whereby upon detonation, anenhanced coalescence of small and large fragments post detonationincreases the post explosion pressurization providing a net increase inkinetic energy.

Some example methods may include utilizing the first annular form todefine part of the second annular containment and/or utilizing thesecond annular form to define part of the first annular containment.

Some example methods may include loading the second multiplicity offragments such that each fragment that is not at a periphery of theordered arrangement is in contact with at least four other adjacentfragments of the same size.

In embodiments of the invention, a method of increasing the kineticenergy of a multiple layered fragmentation device includes providing alayer of smaller fragments each with a mass inside of a layer of largerfragments, the larger fragments having a greater mass than the smallerfragments, and placing explosive material inside the layer inside thelayer of smaller fragments.

In embodiments of the invention, a method of increasing the kineticenergy of a multiple layered fragmentation device includes providing alayer of fragments, the fragments in the layer all having substantiallythe same size, providing fragments with substantially the same mass, thelayer of fragments each with a mass inside of a layer of largerfragments, the larger fragments having a greater mass than the smallerfragments.

Some example methods may include overmolding one of the first annularform and the second annular form over the other of the first annularform and the second annular form.

Some example methods may include utilizing a thermoplastic resin as thefirst annular containment binder. A thermoplastic resin may also beutilized for the second annular containment binder in some examplemethods.

Some example methods may include installing the warhead in a deliverableweapon such as a missile, an artillery round, an aerial bomb, a mortarround, or other fired projectiles, or a grenade. The methods andapparatus herein may also be utilized in a fixed application, such as aland mine or other non-delivered applications.

Some example methods may include selecting a uniform size for the largefragments that is diametrically at least 100 percent larger than theuniform size of the small fragments. Some example methods, may includeselecting a uniform size for the greatest linear dimension of the largefragments that is at least 100 percent larger than the greatest lineardimension of the small fragments. Where there is some variability in thesize of the large fragments and/or the small fragments, the greatestlinear dimension is the mean greatest linear dimension of the largeand/or small fragments.

Some example methods may include utilizing steel for the sphericalfragments of the first multiplicity of spherical fragments and for thesecond multiplicity of spherical fragments.

Some example methods may include utilizing a tungsten alloy for thespherical fragments of the first multiplicity of spherical fragments andfor the second multiplicity of spherical fragments.

In some example embodiments, the maximum diameter of the sphericalfragments of the second multiplicity of spherical fragments is 0.300inches or less.

In some example embodiments, the majority of the large fragments in thesecond set have substantially equal diameters. For example,substantially all of the large fragments in the second set of fragmentsmay have substantially the equal diameters in some embodiments.

In some embodiments an inner layer is sandwiched between an explosiveportion and an outer layer, with portions of the inner layer havingsmaller fragments than a coinciding portion of the outer layer. Otherportions of the inner layer may not have smaller fragments than arespective coinciding portion of the outer layer, for example at cornersor end portions of the inner layer. Thus, in embodiments, a particularpair of layers of fragments need not have uniformity of fragmentationsizes or uniformity of the differentiation between the sizes of theinner and outer layer throughout the respective layers. In embodiments,the inner layer may be comprised of spherical fragments and the outerlayer non-spherical fragments.

Patents incorporated by reference herein for all purposes include: U.S.Pat. Nos. 8,931,415, 7,614,348, 6,981,672, 5,925,845, 5,404,813,5,107,766, and 3,724,379.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings included in the present application are incorporated into,and form part of, the specification. They illustrate embodiments of thepresent disclosure and, along with the description, serve to explain theprinciples of the disclosure. The drawings are only illustrative ofcertain embodiments and do not limit the disclosure.

FIG. 1 is a perspective view showing a partially cross-sectionedwarhead;

FIG. 2 is a perspective view showing a set of preformed fragmentsarranged to form a sleeve;

FIG. 3A is a stylized cross-sectional view illustrating a warheadincluding an explosive charge;

FIG. 3B is a stylized axial view illustrating the operating of thewarhead shown in FIG. 3A;

FIG. 4A is a stylized cross-sectional view illustrating a first warheadconfiguration;

FIG. 4B is a stylized cross-sectional view illustrating a second warheadconfiguration;

FIG. 5A is a graph showing the results of hydrocode analysis performedon the warhead configuration illustrated in FIG. 4A;

FIG. 5B is a graph showing the results of hydrocode analysis performedon the warhead configuration illustrated in FIG. 4B;

FIG. 5C is a legend for the charts of FIGS. 5A and 5B.

FIG. 5D is a theorized pressure curve chart illustrating gainsassociated with embodiments of the invention;

FIG. 6A through 6D are a series of stylized perspective viewsillustrating example methods in accordance with the disclosure andapparatus associated with those methods;

FIGS. 7A through 7G are a series of cross sectional views of a mold andsteps of manufacturing in accord with embodiments of the invention;

FIG. 8 is a side view showing an assembly fabricated using themanufacturing steps illustrated in FIGS. 7A through 7G;

FIGS. 9-11 are perspective views of warheads according to embodiments ofthe invention;

FIG. 12A is a perspective of a missile according to embodiments of theinvention; and

FIG. 12B is a perspective view of an artillery projectile according toembodiments of the invention.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail. It should be understood,however, that the intention is not to limit the invention to theparticular embodiments described. On the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention.

DETAILED DESCRIPTION

In the following description, like reference characters designate likeor corresponding parts throughout the several views. Also in thefollowing description, it is to be understood that such terms as“forward,” “rearward,” “left,” “right,” “upwardly,” “downwardly,” andthe like are words of convenience and are not to be construed aslimiting terms.

FIG. 1 is a perspective view showing a partially cross-sectioned warhead100 in accordance with the present detailed description. Warhead 100 ofFIG. 1 comprises an explosive charge 108. Explosive charge 108 maycomprise a cylindrical container filled with high explosives. A firstsleeve 102 comprising a first set 122 of preformed fragments is disposedabout explosive charge 108. A second sleeve 104 comprising a second set124 of preformed fragments is disposed about both first sleeve 102 andexplosive charge 108. With reference to FIG. 1, it will be appreciatedthat first sleeve 102 is sandwiched between explosive charge 108 andsecond sleeve 104 in the embodiment of FIG. 1. In embodiments, thefragments may be spherical as illustrated and are formed of metal, suchas steel or tungsten.

In the embodiment of FIG. 1, the fragments of first sleeve 102 compriserelatively small fragments 120 and the fragments of second sleeve 104comprise relatively large fragments 130 that are larger than smallfragments 120. In the embodiment of FIG. 1, small fragments 120 are heldin place by a first binding material 132 of first sleeve 102. Largefragments 130 are held in place by a second binding material 134 ofsecond sleeve 104 in the embodiment of FIG. 1. In some embodiments,first binding material 132 and second binding material 134 may comprisethe same material. Upon detonation of explosive charge 108, firstbinding material 132 and second binding material 134 may disintegrate sothat small fragments 120 and large fragments 130 become unbound. Whenthis is the case, small fragments 120 and large fragments 130 are freefrom the binding effect of first binding material 132 and second bindingmaterial 134 after detonation of explosive charge 108. In some exampleembodiments, the first binding material and/or the second bindingmaterial may comprise a thermoplastic resin. In some exampleembodiments, the first binding material and/or the second bindingmaterial may comprise a thermosetting polymer. In some exampleembodiments, the first binding material and/or the second bindingmaterial may comprise an epoxy.

It is contemplated that small fragments 120 and/or large fragments 130may be deformed after detonation of explosive charge 108. In some usefulembodiments, small fragments 120 and large fragments 130 are bothpreformed fragments having sufficient infrangibility and sufficientductility to remain intact after detonation of explosive charge 108.First binding material 132 and second binding material 134 hold thefragments in place until detonation of explosive charge 108. However,first binding material 132 and second binding material 134 lacksufficient strength to remain intact after detonation of explosivecharge 108. Said another way, the binding materials are more frangibleand more brittle than the fragments. In particular, first bindingmaterial 132 is more frangible than small fragments 120 and secondbinding material 134 is more frangible than large fragments 130. In someembodiments, first binding material 132 and second binding material 134obliterate upon detonation of explosive charge 108. Small fragments 120and large fragments 130 are free to move relative to each other afterfirst binding material 132 and second binding material 134 have brokeninto small pieces.

In the embodiment of FIG. 1, each small fragment 120 and each largefragment 130 has a generally spherical outer surface. With reference toFIG. 1, it will be appreciated that small fragments 120 of first sleeve102 are sandwiched between explosive charge 108 and the large fragments130 of second sleeve 104. With first sleeve 102 disposed betweenexplosive charge 108 and second sleeve 104, expanding gases produced byexplosive charge 108 upon detonation will push small fragments 120 intocontact with large fragments 130. In some useful embodiments, smallfragments 120 and large fragments 130 have curved outer surfaces thatfacilitate migration of small fragments 120 into interstitial spacesbetween large fragments 130 when small fragments 120 are forced intocontact with large fragments 130 upon detonation of explosive charge108. The presence of small fragments 120 in the interstitial spacesbetween large fragments 130 may restrict the flow of the expanding gasesbetween large fragments 130. In this way, small fragments 120 and largefragments 130 may cooperate to contain the expanding gases for a longertime before venting of expanding gases has occurred. Increasedcontainment of the expanding gases over a longer period of time mayincrease the kinetic energy transferred to the large fragments 130,while only minimally reducing the kinetic energy of the small fragmentsupon detonation of the explosive charge, thus increasing the totalfragmentation kinetic energy significantly.

Warhead 100 of FIG. 1 includes a sheath 126 that is disposed aboutsecond sleeve 104, first sleeve 102 and explosive charge 108. A firstcap 136 is fixed to a first end of sheath 126 and a second cap 138 isfixed to a second end of sheath 126. In FIG. 1, a detonator 128 ofwarhead 100 can be seen contacting explosive charge 108.

FIG. 2 is a perspective view showing a set of preformed fragments 240arranged to form a sleeve 250. In the embodiment of FIG. 2, sleeve 250includes a generally tubular wall 252 comprising a single layer offragments 240 and each fragment 240 has a generally spherical outersurface. The fragments 240 are stacked so that adjacent pairs offragments 240 are in tangential contact with one another in theembodiment of FIG. 2. The single layer of stacked spheres illustrated inFIG. 2 has a high compressive strength yet almost no shear strength.When sleeve 250 is incorporated into a warhead, a binding material maybe used to hold fragments 240 in place prior to detonation of thewarhead's explosive charge.

In the embodiment of FIG. 2, the fragments 240 of sleeve 250 arearranged in a plurality of axial columns 244 and circumferential rows246. A first circumferential row 246A of sleeve 250 includes pluralityof fragments 240 positioned along a first curved line 256A. Sleeve 250also includes a second circumferential row 246B, a third circumferentialrow 246C, and a fourth circumferential row 246D. Second circumferentialrow 246B comprises a plurality of fragments 240 that are positionedalong a second curved line 256B. Third circumferential row 246Ccomprises a plurality of fragments 240 that are positioned along a thirdcurved line 256C. In the embodiment of FIG. 2, adjacent circumferentialrows, such as second circumferential row 246B and third circumferentialrow 246C are offset from one another in an axial direction. Fourthcircumferential row 246D comprises a plurality of fragments 240 that arepositioned along a fourth curved line 256D.

In the embodiment of FIG. 2, sleeve 250 includes a plurality offragments 240 positioned along a first line 254A to form a first axialcolumn 244A. First line 254A is generally parallel to a centrallongitudinal axis 242 of sleeve 250 in the embodiment of FIG. 2. Aplurality of fragments 240 are positioned along a second line 254B toform a second axial column 244B. In the embodiment of FIG. 2, adjacentaxial columns, such as first axial column 244A and second axial column244B, are offset from one another in a circumferential direction. Aplurality of fragments 240 are positioned along a third line 254B toform a third axial column 244B. A plurality of fragments 240 arepositioned along a fourth line 254B to form a fourth axial column 244B.

FIG. 3A is a stylized cross-sectional view illustrating a warhead 300including an explosive charge 308. FIG. 3B is a stylized axial viewillustrating the operating of the warhead shown in FIG. 3A. Moreparticularly, FIG. 3B provides a stylized illustration showing elementsof warhead 300 after detonation of the explosive charge using solidlines. Dashed lines are used to illustrate the elements of warhead 300prior to detonation of the explosive charge.

With reference to FIG. 3A, it will be appreciated that warhead 300comprises an explosive charge 308. A first sleeve 302 comprising a firstset 322 of preformed fragments is disposed about explosive charge 308. Asecond sleeve 304 comprising a second set 324 of preformed fragments isdisposed about both first sleeve 302 and explosive charge 308. Withreference to FIG. 3A, it will be appreciated that first sleeve 302 issandwiched between explosive charge 308 and second sleeve 304 in theembodiment of FIGS. 3A and 3B.

In the embodiment of FIGS. 3A and 3B, the fragments of first sleeve 302comprise relatively small fragments 320 and the fragments of secondsleeve 304 comprise relatively large fragments 330 that are larger thansmall fragments 320. In the embodiment of FIGS. 3A and 3B, smallfragments 320 are held in place by a first binding material 332 of firstsleeve 302. Large fragments 330 are held in place by a second bindingmaterial 334 of second sleeve 304 in the embodiment of FIGS. 3A and 3B.In some embodiments, first binding material 332 and second bindingmaterial 334 may comprise the same material.

In the embodiment of FIGS. 3A and 3B, small fragments 320 and largefragments 330 are both preformed fragments having sufficient strength toremain intact after detonation of explosive charge 308. For example,small fragments 320 and large fragments 330 may both comprise a tungstenalloy. First binding material 332 and second binding material 334 holdthe fragments in place until detonation of explosive charge 308.However, first binding material 332 and second binding material 334 lacksufficient strength to remain intact after detonation of explosivecharge 308. Said another way, the binding materials are sufficientlyfrangible to disintegrate upon detonation of explosive charge 308.

FIG. 3B is a stylized axial view showing elements of warhead 300 afterdetonation of the explosive charge using solid lines. Dashed lines areused to illustrate the elements of warhead 300 prior to detonation ofthe explosive charge.

With reference to FIG. 3B, it will be appreciated that expanding gases348 produced by the explosive charge upon detonation have pushed smallfragments 320 into contact with large fragments 330. The presence ofsmall fragments 320 are disposed in interstitial spaces 358 betweenlarge fragments 330. The presence of small fragments 320 in interstitialspaces 358 between large fragments 330 may restrict the flow of theexpanding gases 348 between large fragments 330. In this way, smallfragments 320 and large fragments 330 may cooperate to contain expandinggases 348 for a longer time before venting of expanding gases 348 hasoccurred. Increased containment of expanding gases 348 over a longerperiod of time may increase the kinetic energy transferred to largefragments 330, while only reducing the energy of the small fragmentsslightly, upon detonation of explosive charge 308 thus significantlyincreasing the total kinetic energy of the fragmentation.

In some useful embodiments, small fragments 320 and large fragments 330have curved outer surfaces that facilitate migration of small fragments320 into interstitial spaces 358 between large fragments 330 when smallfragments 320 are forced into contact with large fragments 330 upondetonation of explosive charge 308. In the embodiment of FIGS. 3A and3B, each small fragment 320 and each large fragment 330 comprise agenerally spherical outer surface. In the embodiment of FIGS. 3A and 3B,each small fragment 320 comprises a preformed sphere having a firstdiameter DA. Each large fragment 330 comprises a preformed sphere havinga second diameter that is larger than the first diameter DB in theembodiment of FIGS. 3A and 3B.

FIG. 4A is a stylized cross-sectional view illustrating a first warheadconfiguration 460A. FIG. 4B is a stylized cross-sectional viewillustrating a second warhead configuration 460B. Hydrocode analysis wasperformed on both first warhead configuration 460A and second warheadconfiguration 460B. The results of the hydrocode analysis are plotted inFIG. 5A and FIG. 5B.

The first warhead configuration 460A shown in FIG. 4A comprises a firstsleeve 402 comprising a first set 422 of preformed fragments disposedabout an explosive charge 408. A second sleeve 404 comprising a secondset 424 of preformed fragments is disposed about both first sleeve 402and explosive charge 408. In the embodiment of FIG. 4, the fragments offirst sleeve 402 comprise relatively large fragments and the fragmentsof second sleeve 404 comprise relatively small fragments that aresmaller than the fragments of first sleeve 402. First warheadconfiguration 460A includes a first cap 436 that is located at first endof the sleeves and a second cap 438 that is located at a second end ofthe sleeves. In FIG. 4A, a detonator 428 can be seen contactingexplosive charge 408.

The second warhead configuration 460B shown in FIG. 4B comprises a firstsleeve 502 comprising a first set 522 of preformed fragments disposedabout an explosive charge 508. A second sleeve 504 comprising a secondset 524 of preformed fragments is disposed about both first sleeve 502and explosive charge 508. In the embodiment of FIG. 4B, the fragments offirst sleeve 502 comprise relatively small fragments and the fragmentsof second sleeve 504 comprise relatively large fragments that are largerthan the fragments of first sleeve 502. Second warhead configuration460B includes a first cap 536 that is located at first end of thesleeves and a second cap 538 that is located at a second end of thesleeves. In FIG. 4B, a detonator 528 can be seen contacting explosivecharge 508.

With reference to FIG. 4A and FIG. 4B, it will be appreciated thatwarhead configuration 460A and warhead configuration 460B both includean explosive charge. For purposes of the hydrocode analysis, warheadconfiguration 460A and warhead configuration 460B had identicalexplosive charges including the same mass of high explosives. Warheadconfiguration 460A and warhead configuration 460B both include a set ofrelatively small fragments and a set of relatively large fragments. Forpurposes of the hydrocode analysis, warhead configuration 460A andwarhead configuration 460B had identical sets of small and largefragments having identical masses. The primary difference between thetwo configurations was the arrangement of the two sets of fragments.With reference to FIG. 4A and FIG. 4B, it will be appreciated that, inthe first warhead configuration 460A shown in FIG. 4A the largefragments are located between the explosive charge and the smallfragments. It will also be appreciated that, in the second warheadconfiguration 460B shown in FIG. 4B the small fragments are locatedbetween the explosive charge and of the large fragments.

FIG. 5A and FIG. 5B are graphs illustrating the results of the hydrocodeanalysis performed on the two warhead configurations illustrated in FIG.4A and FIG. 4B.

The graph shown in FIG. 5A illustrates the energy profile of the firstwarhead configuration 460A. Fragment kinetic energy vs. polar locationis plotted on this graph. The data points representing the kineticenergy of the large fragments are shown as open triangles and the datapoints representing the kinetic energy of the small fragments are shownas closed triangles.

The graph shown in FIG. 5B illustrates the energy profile of a warheadwith the second warhead configuration 460B. Fragment kinetic energy vs.polar location is plotted in this graph. The data points representingthe kinetic energy of the large fragments are shown as open circles andthe data points representing the kinetic energy of the small fragmentsare shown as closed circles.

The results of the hydrocode analysis showed a substantial increase infragment kinetic energy of the second warhead configuration 460B ascompared to the first warhead configuration 460A.

FIG. 5D is a theorized pressure curve chart illustrating gainsassociated with embodiments of the invention. FIG. 5D includes a firstcurve 546 and a second curve 548, with the second curve representing thetheorized pressure gains associated with embodiments of the invention.

FIG. 6A through FIG. 6D are a series of stylized perspective viewsillustrating example methods in accordance with this detaileddescription and apparatus associated with those methods.

At FIG. 6A, a first sleeve 602 is assembled over an explosive fillcontainer 662. High explosives may be placed in explosive fill container662 at various times without deviating from the spirit and scope of thisdetailed description. In the embodiment of FIG. 6A, first sleeve 602 hasa generally annular shape including an inner surface that defines afirst cavity 668A. Although one half of an annular shape is shown,embodiments will include assembly of complete annular sleeves andpartial annular sleeves. With reference to FIG. 6A, it will beappreciated that first cavity 668A is dimensioned to receive explosivefill container 662. First sleeve 602 comprises a first set 622 ofpreformed fragments. In the embodiment of FIG. 6A, first set 622comprise small fragments 620.

At FIG. 6B, a second sleeve 604 is assembled over first sleeve 602 andexplosive fill container 662. Second sleeve 604 has a generally annularshape including an inner surface 664 that defines a second cavity 668B.It will be appreciated that second cavity 668B is dimensioned to receivefirst sleeve 602 and explosive fill container 662. With reference toFIG. 6C, it will be appreciated that first sleeve 602 will be sandwichedbetween explosive charge 608 and second sleeve 604 after second sleeve604 is assembled over first sleeve 602.

In the embodiment of FIG. 6B, the fragments of first sleeve 602 compriserelatively small fragments 620 and the fragments of second sleeve 604comprise relatively large fragments 630 that are larger than smallfragments 620. In the embodiment of FIG. 6B, small fragments 620 areheld in place by a first binding material 632 of first sleeve 602. Largefragments 630 are held in place by a second binding material 634 ofsecond sleeve 604 in the embodiment of FIG. 6B. In some embodiments,first binding material 632 and second binding material 634 may comprisethe same material.

At FIG. 6C, a sheath 626 is installed over second sleeve 604, firstsleeve 602 and explosive fill container 662. In the embodiment of FIG.6C, sheath 626 has a generally annular or tube-like shape.

At FIG. 6D, a first cap 636 is fixed to a first end of sheath 626 and asecond cap 638 is fixed to a second end of sheath 626. First cap 636,second cap 638 and sheath 626 may cooperate to contain, secure andprotect all components located therein.

FIGS. 7A through 7G are a series of cross sectional views of a mold andsteps of manufacturing in accord with embodiments of the invention.

At FIG. 7A, a mold 770 is provided. With reference to FIG. 7A, it willbe appreciated that mold 770 defines a first annular containment 782. Inthe embodiment of FIG. 7A, mold 770 comprises a first core 772, a moldbody 780, and a first plug 776. First core 772, mold body 780, and firstplug 776 cooperate to define the first annular containment 782 in theembodiment of FIG. 7A. With reference to FIG. 7A, it will be appreciatedthat the first plug 776 defines passageways that fluidly communicatewith the first annular containment 782.

At FIG. 7B, a first multiplicity of spherical fragments of a uniformfirst size are loaded within the first annular containment 782. In theexemplary embodiment of FIG. 7B, the first multiplicity of sphericalfragments are arranged to form a wall comprising a single layer offragments. The fragments are arranged so outer spherical surfaces ofadjacent pairs of fragments are in tangential contact with one anotherin the embodiment of FIG. 7B.

At FIG. 7C, the first annular containment 782 is filled with a firstannular containment binder 786. In the illustrative embodiment of FIG.7C, the first annular containment binder 786 has a flowable condition sothat the first annular containment binder flows into space betweenfragments. In this way, the first annular containment binder 786 fillsthe volume of the first annular containment that is not occupied byfragments so that the first annular containment binder 786 may hold thefragments in place after the first annular containment binder 786 hasbeen allowed to harden. The hardened first annular containment binder786 and spherical fragments embedded within the first annularcontainment binder 786 form a first sleeve 702. With reference to FIG.7C, it will be appreciated that first sleeve 702 generally has the shapeof the first annular containment 782.

At FIG. 7D, the first mold insert 776 and the first core 772 are removedfrom the mold 770. A second core 774 is placed in the position formerlyoccupied by the first core 772. With reference to FIG. 7D, it will beappreciated that the second core 774 and first sleeve 702 defined asecond annular containment 784. At FIG. 7D, a second multiplicity ofspherical fragments of a uniform second size are loaded within thesecond annular containment 784.

At FIG. 7E, a second mold insert 778 has been placed in the positionformerly occupied by first mold insert 776. Second plug 778 definespassageways that fluidly communicate with the second annular containment784.

At FIG. 7F, the second annular containment 784 is filled with a secondannular containment binder 788. In the illustrative embodiment of FIG.7F, the second annular containment binder 788 has a flowable conditionso that the second annular containment binder 788 flows into spacebetween fragments. In this way, the second annular containment binder788 fills the volume of the second annular containment that is notoccupied by fragments so that the second annular containment binder 788will hold the fragments in place after the second annular containmentbinder 788 has been allowed to harden. The hardened second annularcontainment binder 788 and spherical fragments embedded within thesecond annular containment binder 788 form a second sleeve 704. Withreference to FIG. 7F, it will be appreciated that second sleeve 704generally has the shape of the second annular containment 784.

At FIG. 7G, the first sleeve 702 and the second sleeve 704 have beenremoved from the mold 770. With reference to FIG. 7G, it will beappreciated that second sleeve 704 defines a cavity 790. A warhead inaccordance with this detailed description may include first sleeve 702,second sleeve 704 and an explosive charge disposed in cavity 790. Theexplosive charge may comprise, for example, a container filled with highexplosives.

With continuing reference to FIGS. 7A through 7G, it will be appreciatedthat a method of manufacturing a warhead in accordance with thisdetailed description may include loading a first multiplicity ofspherical fragments of a uniform first size within a first annularcontainment in an ordered arrangement and filling the first annularcontainment with a first annular containment binder for at leastsubstantially covering the first multiplicity of spherical fragments.The first annular containment binder may have a flowable condition tofacilitate filling of the first annular containment. The method mayinclude allowing the binder to harden wherein the spherical fragmentsare embedded within the first annular containment binder in a firstannular form having the shape of the first annular containment. Thisexample method may also include loading a second multiplicity ofspherical fragments of a uniform second size within a second annularcontainment having a wall surface that corresponds to a wall surface ofthe first annular containment. This method may additionally includefilling the second annular containment with a second annular containmentbinder for at least substantially covering the multiplicity of sphericalfragments. The second annular containment binder may have a flowablecondition to facilitate filling of the second annular containment. Themethod may include allowing the second annular containment binder toharden wherein the spherical fragments are embedded within the secondannular containment binder in a second annular form with the shape ofthe second annular containment. An explosive material may be positionedwithin a cavity defined by the annular forms. The first annular form,the second annular form and the explosive material may be positionedwithin a housing with one annular form interior to the other annularform.

Some example methods may include utilizing the second annularcontainment to define part of the first annular form and/or utilizingthe first annular containment to define part of the second annular form.

Some example methods may include loading the second multiplicity offragments such that each fragment that is not at a periphery of theordered arrangement is in contact with a plurality of other adjacentfragments of the same size.

Some example methods may include overmolding one of the first annularform and the second annular form over the other of the first annularform and the second annular form.

Some example methods may include utilizing a thermoplastic resin as thefirst annular containment binder. A thermoplastic resin may also beutilized for the second annular containment binder in some examplemethods.

Some example methods may include installing the warhead in a deliverableweapon such as a missile, an artillery round, an aerial bomb, a mortarround, or a grenade.

FIG. 8 is a side view showing an assembly fabricated using themanufacturing steps illustrated in FIGS. 7A through 7G. An outer surfaceof first sleeve 702 is visible in FIG. 8 FIGS. 9-11 are perspectiveviews of illustrative warheads according to embodiments of theinvention. With reference to FIGS. 9-11, it will be appreciated thatwarheads may have various three dimensional shapes without deviatingfrom the spirit and scope of this detailed description.

FIG. 12A is a perspective of a missile according to embodiments of theinvention. The missile of FIG. 12A may include a warhead such as theillustrative warheads discussed in this detailed description. Themissile may deliver the warhead to a precise location near a target.Once the warhead is near the target, the explosive charge may bedetonated. The warhead may include concentric annular sleeves that upondetonation provide placement of smaller fragments of an inner annularsleeve interstitially with respect to larger fragments of an outerannular sleeve in an expanding fragmentation curtain that containsexpanding gases to increase the pressure of the explosion and thekinetic energy transferred to the fragments. The fragments mayneutralize the target.

FIG. 12B is a perspective view of an artillery projectile according toembodiments of the invention. The artillery projectile of FIG. 12B mayinclude a warhead such as the illustrative warheads discussed in thisdetailed description. Warheads in accordance with this detaileddescription may be carried by various deliverable weapons. Examples ofdeliverable weapons include missiles, artillery rounds, aerial bombs,mortar rounds, and grenades. Warheads in accordance with this detaileddescription may also be incorporated into non-deliverable weapons. It iscontemplated that warheads in accordance with this detailed descriptionmay be incorporated into landmines. In some applications, a warhead inaccordance with this detailed description may a generally planar shaperather than an annular shape.

Patents incorporated by reference herein for all purposes include U.S.Pat. Nos. 8,931,415; 7,614,348; 6,981,672; 5,925,845; 5,404,813;5,107,766; and 3,724,379.

The descriptions of the various embodiments of the present disclosurehave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A warhead, comprising: an explosive charge; afirst wall comprising a first set of fragments disposed adjacent saidexplosive charge; a second wall comprising a second set of fragments anddisposed adjacent said first wall, said second wall defining an innersurface that dimensionally corresponds to an outer surface of said firstwall with no explosive material positioned between said first wall andsaid second wall; said first set of fragments comprising small fragmentsand said second set of fragments comprising large fragments, whereinvolumetrically, any one of said large fragments is at least 300% largerthan any one of said small fragments.
 2. The warhead of claim 1,wherein: said first wall defines one of a sleeve and an ogive thatextends about said explosive charge; and said second wall defines one ofa sleeve and an ogive that extends about said first wall.
 3. The warheadof claim 1, wherein said first set of fragments are of uniform size andsaid second set of fragments are of uniform size.
 4. The warhead ofclaim 1, wherein said first set of fragments are spherical and saidsecond set of fragments are spherical.
 5. The warhead of claim 1,wherein said first set of fragments and said second set of fragmentsdefine a same shape.
 6. The warhead of claim 1, wherein volumetrically,said large fragments are at least 600% larger than said small fragments.7. The warhead of claim 1, wherein said first set of fragments areembedded in a binder and said second set of fragments are embedded in abinder.
 8. The warhead of claim 1, wherein said first wall defines aplanar shape.
 9. A warhead, comprising: a first wall disposed between anexplosive charge and a second wall, said first wall including aplurality of large fragments that defining a plurality of interstitialspaces therebetween, said second wall including a plurality of smallfragments, each small fragment of said plurality of small fragmentsbeing smaller in volume than each large fragment of said plurality oflarge fragments, wherein, upon detonation of said explosive charge, saidwarhead is configured so that said plurality of small fragments areforced into said plurality of interstitial spaces of said first wall andinto contact with said plurality of large fragments to temporarilyrestrict flow of expanding gases between said plurality of largefragments of said first wall.
 10. The warhead of claim 9, wherein saidplurality of large fragments and said plurality of small fragmentsinclude curved surfaces to facilitate migration of said second set offragments into said plurality of interstitial spaces when said pluralityof small fragments are forced into contact with said plurality of largefragments upon detonation of said explosive charge.
 11. The warhead ofclaim 9, wherein a binder is disposed in said plurality of interstitialspaces.
 12. The warhead of claim 9, wherein said first wall and saidsecond wall each define one of a planar shape, a sleeve, and an ogive.13. The warhead of claim 9, wherein volumetrically, any one of saidlarge fragments is at least 300% larger than any one of said smallfragments.
 14. A warhead having fragments with enhanced acceleration andvelocity upon explosion of the warhead, the warhead having a layer ofsmaller fragments positioned between a layer of larger fragments and awarhead explosive material, volumetrically, the mean size of the smallerfragments is less than the mean size of the larger fragments, andwherein no explosive material is positioned between the layer of smallerfragments and the layer of larger fragments, whereby, upon an explosionof the explosive material, the smaller fragments and larger fragmentscoalesce providing an enhanced dynamic containment of expanding gases ofthe explosion increasing the pressure of the explosion and the kineticenergy of the fragments.
 15. The warhead of claim 14, wherein upon theexplosion, the smaller fragments move into interstitial areas of thelarger fragments.
 16. The warhead of claim 14, wherein the warhead has aplanar shape.
 17. The warhead of claim 15, wherein the layer of smallerfragments and the layer of larger fragments form concentric annularsleeves.
 18. The warhead of claim 15, wherein the layer of smallerfragments further comprises a binder encasing the smaller fragments. 19.The warhead of claim 15, wherein the fragments of the layer of smallerfragments are uniformly shaped.
 20. The warhead of claim 19, wherein thefragments of the layer of smaller fragments are non spherical.